1. Field of the Invention
The present invention relates to high speed data communication (e.g., 1 G-bit/second or higher). In particular, the present invention relates to a bidirectional data communication protocol for communicating between a serializer and a deserializer.
2. Discussion of the Related Art
Transmitting a multi-bit data word in parallel over a number of conductors is costly because each transmitted bit requires a transmitter and a receiver circuit, in addition to the many conductors in a parallel cable. In addition, the bits of the data word may arrive at the receiver skewed or delayed in time relative to each other. The data rate is therefore limited by any margin of error that must be provided to compensate for such skews. One method in the prior art to avoid the high cost of parallel data transmission serializes the parallel data at the transmitter into a single data stream and deserializes the data stream back into parallel data at the receiver. In many applications, a small amount of control information (relative to the data transmitted) may still be required from the receiver. The cost savings of serialization is partly offset by providing a separate channel for sending such control information in the opposite direction.